Optical and EPR spectroscopic studies of silver clusters in Ag,Na-Y zeolite by γ-irradiation

Abstract

Silver clusters in γ-irradiated faujasite (zeolite Y) have been studied and characterized by optical absorption and electron paramagnetic resonance (EPR) spectroscopies. Depending upon the composition and conditions of preparation (silver and water content, irradiation dose), different silver cluster species and silver particles were observed. A new silver cluster species inside the faujasite lattice, which corresponds to a low silver content, is presented. Optical absorption bands at 265 and 305 nm have been observed and assigned to trimeric silver ions (Ag₃²⁺). In addition, EPR data of the dehydrated low-silver-content samples indicated the formation of trimeric silver clusters (Ag₃⁰) with an isotropic EPR signal (g_iso= 2.034, coupling constant of 90–100 G) and no detectable hyperfine splitting. These silver clusters are probably linear.